Re: [Xen-users] 2.6.31.6 pv_ops can't boot pv_ops DomU kernel

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Fri, Jan 29, 2010 at 10:16:03AM +0100, Stefan Kuhne wrote:
> Am 29.01.2010 10:10, schrieb Pasi Kärkkäinen:
> > On Fri, Jan 29, 2010 at 09:33:28AM +0100, Stefan Kuhne wrote:
> >>
> >>>> [    0.071368] NET: Registered protocol family 1
> >>>> [    0.071490] Trying to unpack rootfs image as initramfs...
> >>>> [    0.088897] Freeing initrd memory: 5740k freed
> >>>
> >>>
> >>> So initrd execution starts..
> >>>
> >>> Is this the same initrd image you use for dom0?
> >>>
> >> Yes.
> >>
> > 
> > Try generating a new initrd *in* the guest, *for* the guest.
> > 
> How can i to it?
> I make it by hand without any "mk..." tools.
> 

some distros have "mkinitrd", and some have "mkinitramfs".
Check the documentation of your distro.

> >>>> [    0.280801] Freeing unused kernel memory: 388k freed
> >>>> [    0.283323] Write protecting the kernel text: 3816k
> >>>> [    0.284369] Write protecting the kernel read-only data: 1768k
> >>>>
> >>>
> >>> I wonder why it doesn't mount/switch the root here..
> >>>
> >> I to ;).
> >>
> > 
> > I hope the output isn't redirected to the netconsole.. 
> > that would explain the lack of needed console output.
> > 
> The DomU has no CPU-Usage in xentop.
> 

Hmm.. does the domU crash? Or it just stays in "xm list" or "xm top" forever?
Does "xm log" have something related?


> >>> Do you have xenconsoled running in dom0? Do consoles of other guests work 
> >>> OK?
> >>>
> >> 1st: I think so.
> >> 2nd: I've only this domU for testing.
> >> With an older 2.6.24-24-xen (Ubuntu) starts this DomU.
> >>
> > 
> > It definitely sounds like an initrd problem to me.
> > Try with a new initrd.
> > 
> If had to update the initrd base for this Kernel.
> 
> For what does i need an initrd on DomU?
> 

most (all?) distros nowadays build modular kernels, so the kernel
has only the minimum required drivers built-in to the kernel,
and the rest is built as kernel modules.

initrd image is a small filesystem that has a bunch of kernel modules,
and a script to load them + set up the root filesystem.

So basicly bootloader (grub/pygrub or xen pv bootloader) sets up the 
kernel and initrd in memory, and boots the kernel.

Kernel then extracts the initrd from the memory, and executes the script
in the initrd. The script then loads the necessary drivers for *that*
particular server hardware or a virtual machine to access the actual
root disk, and then the script mounts the root disk so the actual linux 
distribution can be started from the real root disk.

So the initrd image you use must be suitable for the Xen domU and load 
the required kernel modules (possibly xenblk) and set up the xen xvd-disks!

(Although it seems yours already did that, or the xenblk is compiled into the 
kernel)

-- Pasi


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